which battery should i choose?

i run a dragster with a 555 bbc, run all the good stuff like msd digital programmable 7,pro cube delay,brp electric shift,starting line auto start,all digital led gauges(tac,oil,temp,trans temp,volt,vac,oil temp)also run head lights and digital dial in board.
i ran the red top optima last year and noticed the volts getting low even with charging between rounds,so i thought i would try the optima group31a battery,battery was delivered and i was suprised to find out this thing weighs 59.8 lbs(should have read the specs better)would like to run alternator but have no room.
so does any body have any good sugggestions on what i should try??
i cant afford to give a grand for those v batteries. thanks